It is that, owing to profound but intelligible causes, the contrast which necessarily obtains between the sexes in respect of their vital expenditure is most marked in the case of our own species. It is one of the conditions of progress that the young of the higher species make more demands upon their mothers than do the young of humbler forms. In other words, progress in the world of life has always leant upon and been conditioned by motherhood. Thus, as one has so frequently asserted in reference to the modern campaign against infant mortality, the young of the human species are nurtured within the sacred person—the therefore sacred person—of the mother for a longer period in proportion to the body weight than in the case of any other species; and the natural period of maternal feeding is also the longest known. On the other hand, the physical demands made by parenthood upon the male sex are no greater in our case than in that of lower forms; though upon the psychical plane the great fact of increasing paternal care in the right line of progress may never be forgotten. But thus it follows that the law of conservation, asserting that what is spent for self cannot be kept for the race, and that if the demands of the future are to be met the present must be subordinated, not merely applies to woman, but applies to her in unique degree. There are grounds, also, for believing that what is demonstrably and obviously true on the physical plane has its counterpart in the psychical plane; and that, if woman is to remain distinctively woman in mind, character, and temperament, and if, just because she remains or becomes what she was meant to be, she is to find her greatest happiness, she must orient her life towards Life Orient, towards the future and the life of this world to come. Some such doctrines may help us at a later stage to decide whether it be better that a woman should become a mother or a soldier, a nurse or an executioner.
CHAPTER V
THE DETERMINATION OF SEX
We must regard life as essentially female, since there is no choice but to look upon living forms which have no sex as female, and since we know that in many of the lower forms of life there is possible what is called parthenogenesis or virgin-birth. It has, indeed, been ingeniously argued by a distinguished American writer, Professor Lester Ward,[4] that the male sex is to be looked upon as an afterthought, an ancillary contrivance, devised primarily for the advantages of having a second sex—whatever those advantages may exactly be; and secondarily, one would add, becoming useful in adding fatherhood to motherhood upon the psychical plane of post-natal care and education as well.
But whatever was the historical or evolutionary origin of sex, we may here be excused for attaching more importance—for it is of great practical consequence—to the origin or determination of sex in the individual. At what stage and under what influences did the child that is born a girl become female? To what extent can we control the determination of sex? Why are the numbers of the sexes approximately so equal? What determines the curious disproportions observed in many families, which may be composed only of girls or only of boys; and, as is asserted, also observed after wars and epidemics or during sieges, when an abnormally high proportion of boys is said to be born? These are some of the deeply interesting questions which men have always attempted to answer—with the beginnings of substantial success during the present century at last.
In general it is true that, the more we learn of the characters and histories of living beings, the more importance we attach to nature or birth and the less to nurture or environment, vastly important though the latter be. Thus to the student of heredity nothing could well seem more improbable, at any rate amongst the higher animals, than that characters so profound as those of sex should be determined by nurture. He simply cannot but believe that the sex of the individual is as inborn as his backbone, and as incapable of being created by varying conditions of nurture. The causation of sex is therefore really a problem in heredity; and we may most confidently assert, in the first place, that the sex of every human being is already determined at the moment of conception when, indeed, the new individual is created: determined then by the nature and constitution of the living cells—or of one of them—which combine to form the new being. Subsequent attempts to affect the sex, as by means of the mother's diet and the like, are palpably hopeless from the outset and always will be. This is by no means to say that conditions affecting the mother—as, for instance, the semi-starvation of a prolonged siege—may not affect the construction of the germ-cells which she houses, and which are constantly being formed within her from the mother germ-cells, as they are called. But any given final germ-cell, such as will combine with another from an individual of the opposite sex to form a new being, is already determined, once for all, to be of one sex or the other. We naturally ask, then, how the two parents are concerned in this matter; and the first remarkable answer returned by the Mendelian workers during the last three or four years is that it is the mother who determines the sex of her children in the case of all the higher animals. Her contribution to the new being is called the ovum, and it is believed that ova are of two kinds, or, we are quite right in saying, of two sexes.
Those who are now working at these problems experimentally, actually seeing what happens in given cases, and whom we may for convenience call Mendelians after the master who gave them their method and their key, have latterly obtained results the main tenour of which must be stated here, as they indicate the lines of a portion of the succeeding argument. The task was to attack experimentally the determination of sex—a fascinating problem for which so many solutions that failed to hold water have been found, but hitherto no others. In finding the answer to it, as they appear certainly to have done so far as the higher animals are concerned, the Mendelians are also beginning to ascertain, as we shall see, certain basal facts as to the composition or constitution of the individual; and to us, who wish to know exactly what a woman is, and what she is as distinguished from a man, this discovery is of the most vital importance. The experimental facts are not yet numerous, and if they were not consonant with facts of other orders, it would be rash to proceed; but it will be evident, in the sequel, that common experience is well in accord with the experimental evidence.
It appears that, amongst at any rate the higher animals, the sex of offspring is determined by the nature of the mother's contribution. The cell derived from the father is always male—as goes without saying, we might add, if we knew little of the subject. But the ovum, the cell derived from the mother, may carry either femaleness or maleness. When an ovum bearing maleness meets the invariably maleness-bearing sperm, the resultant individual is a male, of course, and he is male all through. But when an ovum bearing femaleness meets a sperm, the resulting individual is female, femaleness being a Mendelian "dominant" to maleness; if both be present, femaleness appears. The female, however, is not female all through as the male is male all through. So far as sex is concerned, he is made of maleness plus maleness; but she is made of femaleness plus maleness. In Mendelian language the male is homozygous, so-called "pure" as regards this character. But the female is heterozygous, "impure" in the sense that her femaleness depends upon the dominance of the factor for femaleness over the factor for maleness, which also is present in her. In the Mendelian terminology, she is an instance of impure dominance. The observed practical equality in the numbers of the two sexes is in exact accord with this interpretation of the facts, this proportion being the expected and observed one in many other cases which doubtless depend upon parallel conditions of the reproductive cells.